US Divers Micra servicing

[tom lauder]

Morning all

I'm hoping some of the experts here can help me with something.

I have serviced my pair of Micras allw went well stripping, bath in the ultrasonic, install the servcice kit and reassemble. I bought these cheap as something to practice on but also with the hope that i can dive them as my memory from when i dived before was that they were quite nice regs.

The question I have is around how far in do you screw the crown and adjuster screw on reassembly before you do the final adjustment and testing. From looking at ScubaTools it appears there is a tool that allows you to screw each part in until the shoulder of the tool touches.

Seat Preset Tool. Micra

If I have to buy the tool I will but being in Canada the exchange rate and shipping make it quite expensive for what isessentially a gauge with 2 dimensions. I have the means to make it if I know the dimensions or even just use a caliper for now.



So does anyone know the spec. depth or maybe have the tool and is willing to share the dimensions.

Any help much appreciated

Tom

 

[The Chairman]

The tubes are easiest to assemble if you Screw it in until the lever is flush with the tube. I actually Hold the lever down as I am screwing the orifice in, so it won't needlessly crease the seat. I also make sure the adjustng know is turned all the way out (CCW). Once the tube is in and the gland nut is tightened (don't over tighten and so crack the housing), hold it in again and loosen it up until the lever is almost at it's apex. Let go of the lever and slowly back out the orifice just until the lever reaches reaches its apex. I usually have the diaphragm side facing up and am looking across the plane. When it stops moving up, I tweak it back in an eighth turn. The lever should have just the tiniest amount of wiggle to it. If you do this just right, you won't have to make any further adjustments.

Test #1: Put your lips up to the orifice and blow. You should feel that it's "solid" and that no air passes through. However, a slight push on the lever should allow air to pass a bit. Fully depressed, it should allow a lot more through.

Now reassemble the diaphragm and the cover, attach it to a first stage. HOLD THE PURGE DOWN as you crack open the valve. Once you hear the beginnings of a hiss, let go of the purge. Open up the tank valve fully and attach an IP gauge to check that the first stage has been set right. Take at least a dozen breaths on the reg, but don't hyperventilate. Repeat this two or three times to set the seat.

Test #2: Fill a bucket of water to near the top. With the diaphragm pointing downwards, slowly immerse the first stage into the water until the you just start to hear it hiss. Note where this is on mouthpiece. Measure from where the diaphragm sits (near the bottom of the cover) and that point to determine your cracking pressure. It should anywhere from 7/8" to an 1 1/4". Now turn the adjustment knob all the way in and repeat the procedure. If you've set it right, it won't leak at all and water will actually start flowing into the mouthpiece.

 

[JackD342]

Morning all

I'm hoping some of the experts here can help me with something.

I have serviced my pair of Micras allw went well stripping, bath in the ultrasonic, install the servcice kit and reassemble. I bought these cheap as something to practice on but also with the hope that i can dive them as my memory from when i dived before was that they were quite nice regs.

The question I have is around how far in do you screw the crown and adjuster screw on reassembly before you do the final adjustment and testing. From looking at ScubaTools it appears there is a tool that allows you to screw each part in until the shoulder of the tool touches.

Seat Preset Tool. Micra

If I have to buy the tool I will but being in Canada the exchange rate and shipping make it quite expensive for what isessentially a gauge with 2 dimensions. I have the means to make it if I know the dimensions or even just use a caliper for now.



So does anyone know the spec. depth or maybe have the tool and is willing to share the dimensions.

Any help much appreciated

Tom

First, let me set some expectations: I am an Aqualung dealer and an authorized service technician. As such, I am riding a fine line where I do not provide any documentation, service kits, or otherwise enable service by an unauthorized individual. However, I do pass along specific tidbits of knowledge when and where I can when I see someone may be heading down the wrong path, to steer them back.

In the case of the Micra, I would strongly suggest that you only adjust it according to manufacturer's directions rather than generalized "they are all the same" instructions. Aside from the couple of specialized tools, the Micra is an odd bird in that the specified multi-step adjustment process includes changing the 1st stage IP a couple of times during the process in a very specific manner.

I cannot speak to what would result if adjusted in a more typical fashion, as I follow the manufacturer's procedure.

 

[tom lauder]

Thank you Sir very informative. One question mine are the older pre adjustable micras do these instructions hold true for those?

I also make sure the adjustng know is turned all the way out (CCW)

The tubes are easiest to assemble if you Screw it in until the lever is flush with the tube. I actually Hold the lever down as I am screwing the orifice in, so it won't needlessly crease the seat. I also make sure the adjustng know is turned all the way out (CCW). Once the tube is in and the gland nut is tightened (don't over tighten and so crack the housing), hold it in again and loosen it up until the lever is almost at it's apex. Let go of the lever and slowly back out the orifice just until the lever reaches reaches its apex. I usually have the diaphragm side facing up and am looking across the plane. When it stops moving up, I tweak it back in an eighth turn. The lever should have just the tiniest amount of wiggle to it. If you do this just right, you won't have to make any further adjustments.

Test #1: Put your lips up to the orifice and blow. You should feel that it's "solid" and that no air passes through. However, a slight push on the lever should allow air to pass a bit. Fully depressed, it should allow a lot more through.

Now reassemble the diaphragm and the cover, attach it to a first stage. HOLD THE PURGE DOWN as you crack open the valve. Once you hear the beginnings of a hiss, let go of the purge. Open up the tank valve fully and attach an IP gauge to check that the first stage has been set right. Take at least a dozen breaths on the reg, but don't hyperventilate. Repeat this two or three times to set the seat.

Test #2: Fill a bucket of water to near the top. With the diaphragm pointing downwards, slowly immerse the first stage into the water until the you just start to hear it hiss. Note where this is on mouthpiece. Measure from where the diaphragm sits (near the bottom of the cover) and that point to determine your cracking pressure. It should anywhere from 7/8" to an 1 1/4". Now turn the adjustment knob all the way in and repeat the procedure. If you've set it right, it won't leak at all and water will actually start flowing into the mouthpiece.

 

[JackD342]

I don't know what you mean by pre-adjustable. Are you referring to the Venturi dive/pre-dive switch on the top?
The document I just referenced does include the Venturi, and is old enough that it is branded US Divers and not Aqualung.

Added: whoops. I don't think your question was directed my way. But reply if you like.

 

[tom lauder]

Thanks

I'm aware of the restrictions on dealers and am not asking anyone to jeapordise their livelihood for my benefit.

First, let me set some expectations: I am an Aqualung dealer and an authorized service technician. As such, I am riding a fine line where I do not provide any documentation, service kits, or otherwise enable service by an unauthorized individual. However, I do pass along specific tidbits of knowledge when and where I can when I see someone may be heading down the wrong path, to steer them back.

In the case of the Micra, I would strongly suggest that you only adjust it according to manufacturer's directions rather than generalized "they are all the same" instructions. Aside from the couple of specialized tools, the Micra is an odd bird in that the specified multi-step adjustment process includes changing the 1st stage IP a couple of times during the process in a very specific manner.

I cannot speak to what would result if adjusted in a more typical fashion, as I follow the manufacturer's procedure.

 

[tom lauder]

I was referencing Chairmans statement that he makes these adjustments with the adjusting knob all the way out which implies to me the later micra adj which has the venturi control on the top and the adjustment knob on the side as opposed to my micra which only has the venturi control on the top.

not the earler micra

I don't know what you mean by pre-adjustable. Are you referring to the Venturi dive/pre-dive switch on the top?
The document I just referenced does include the Venturi, and is old enough that it is branded US Divers and not Aqualung.

Added: whoops. I don't think your question was directed my way. But reply if you like.

 

[The Chairman]

One question mine are the older pre adjustable micras do these instructions hold true for those?

Except for playing with the knob... Yes. FWIW, the first Micra I ever owned (1999?) was adjustable. I think that the non adjustable Micras came later. I dove mine for years and loved it as well as the Cousteau first stage.

as opposed to my micra which only has the venturi control on the top.

All the Micras I have seen had the venturi block. It won't affect the cracking depth one whit. BTW, if you feel you need to adjust if after the fact, less is best. Use 1/8 turns and take your time. Don't tighten the hose onto the second stage until you're done.

 

[axxel57]

Thank you Sir very informative. One question mine are the older pre adjustable micras do these instructions hold true for those?

Haven't found time to work on my Micras, so can't help with my own experience in this case....
The Service Manual for the Non Adjustable Micra (US Divers 1992) might help.....
Send me a PM.....